Dryer having removable heating units



Marqh l0, 1970 E. J. zlMMl-:RMANN 3,499,232

' DRYER HAVING REMovABLE HEATING UNITS Filed Nov. 13. 19617 2 Sheets-Sheet 1 FIG. 5. l' I fl z l I' \y 'IMI'. lj x EDUARD J. ZIMMERMA NN BY ATTORNEY E. J. ZIMMERMANN' DRYER HAVING REMOVABLE HEATING UNITS March 10, 1970 2 Sheets-.Sheet 2 Filed "Nov, 13, 1967 IN VEN TOR EDUARD J. ZIMMERMANN BV ATTORNEY United States Patent O f lU.S. Cl. 34-68 4 Claims ABSTRACT F THE DISCLOSURE A dryer for drying moving webs or other articles by the combination of infra-red radiations and air flow has a downwardly opening elongated housing in which one or more heating units each having a metal casing are received with clearance between the sides of the casing and housing so that air admitted to the housing above the casing issues through such clearance after absorbing heat from the casing which is heated by means therein emitting infra-red radiations from the bottom thereof, and each casing is removably mounted in the housing by laterally projecting ears received in slots of resiliently flexible portions of mounting brackets carried by the housing and which can be displaced away from the casing to release the ears.

This invention relates generally to apparatus for highspeed drying and more particularly to apparatus in which high-speed drying of moving webs or the like is accomplished by a combination of radiant heat, such as, infra` red radiation, and air flow.

In many industrial applications today there is an ever increasing need to increase drying speed in order to take advantage of increased production speed and capacity. In order to increase the drying speed, radiant energy is imparted t-o the molecules of moisture on the surface to be dried in order to overcome the holding power of the potential energy bond whereupon evaporation of the moisture commences and the resulting gaseous rn-olecules of moisture are removed from the vicinity of the surface being dried by means of warm air flows so that such moisture cannot re-condense on the surface being dried.

Moving webs which are to be dried by the combination of infra-red radiation `and air flow frequently have very large widths, for example, as in paper-making machinery, yand the heating units for directing infra-red radiation against such webs and for heating the air ows must extend over such large widths. The resistance heating wires that are included in such heating units are the most frequent source of trouble in drying apparatus of the described character and, upon a failure thereof, it is necessary' to replace the respective heating unit. In existing drying apparatus employing the combination ofl infra-red radiation and air flow for high-speed drying of moving webs or other articles, the replacement of a heating unit upon the failure of its resistance heating elements or wires is a tedious and time consuming operation, and therefore requires that the associated production line be rendered inoperative for relatively long periods.

Accordingly, it is an object of this invention to provide apparatus for high-speed drying which utilizes the combination of infra-red radiation and Iair flow, and which is constructed and arranged so that the individual heating units thereof may be easily and rapidly replaced.

In accordance with yan aspect of this invention, an apparatus for the high-speed drying of moving webs and other articles by the c-ombination of infra-red radiation and air flow comprises an elongated housing which is open at .the bottom to receive one or more heating units 3,499,232 Patented Mar. 10, 1970 each having a metal casing dimensioned to lit in the housing with substantial clearance between the sides of of the housing and casing so that air admitted to the housing above the casing issues through such clearance after absorbing heat from the casing which is heated by means in the latter emitting infra-red radiation from the bottom thereof, and each casing is removably mounted in the housing by laterally projecting ears and associated mounting brackets secured to the adjacent sides of the housing and including resiliently flexible portions biased toward the casing and having slots to receive the ears, such flexible portions of the mounting brackets being displaceable away from the casing to release the ears and thereby permit removal of the heating unit from the housing.

In a preferred embodiment of the invention, the resiliently fiexible portion of each mounting bracket is in the form of a strip inclined away from the adjacent side of the housing in the upward direction `and having its slot in the upper part of the strip so that, during upward insertion of the heating unit into the housing, the ears of the casing can outwardly deflect the resilient strips of the brackets until such ears are received in the associated slots.

It is a further feature of this invention to provide the resilient strip of each mounting bracket with an inwardly directed ange at its upper end to engage over the top of the casing of the heating unit for limiting the upward movement of such casing to a position where the ears thereof register with the slots of the mounting brackets.

The above, and other objects, features and advantages of the present invention, will be apparent in the following detailed description of an illustrative embodiment of the invention which is to be read in connection with the accompanying drawings, wherein:

FIG. l is a longitudinal sectional view of a dryer in accordance with this invention, which sectional View is taken along the line 1-1 on FIG. 2;

FIG. 2 is a horizontal sectional view taken along the line 2--2 on FIG. l;

FIG. 3 is an enlarged transverse sectional view taken along the line 3-3 on FIG. 1;

FIG. 4 is an enlarged, fragmentary perspective vieW illustrating details of the structure by which each heating unit is mounted within the housing of the drying apparatus in accordance lwith this invention;

FIG. 5 is a fragmentary sectional view corresponding to a portion of FIG. 3, and illustrating the manner in which the mounting for each heating unit may be disengaged for easy removal of the heating unit from the housing; and

FIG. 6 is a view similar to that of FIG. 5, but illustrating the manner in which each heating Vunit may be installed in the housing.

Referring to the drawings in detail, and initially to FIGS. 1 and 2. thereof, it will be seen that a high-speed dryer 10 in accordance with the present invention is shown to comprise a metal housing or shell 11 in the form of an elongated box having a top wall 12 and depending side and end walls 13 and 14 and which is open at the bottom. The housing 11 is suitably suspended from a ceiling or framework (not shown) so as to open downwardly above a moving web W or other article to be dried, and the housing 11 is longitudinally dimensioned so as to extend laterally across the entire width of the web W.

Mounted within housing 11, as hereinafter described in detail, are a number of heating units 1S which are arranged end-to-end along the length of the housing. Each of the heating units 15 is shown to comprise a rectangular metal casing 16 dimensioned to fit in housing 11 with 3 substantial clearance 17 (FIG. 2 and 3) between the sides of casing 16 and the adjacent side walls 13 of housing 11. Further, casing 16 is of a height substantially smaller than that of housing 11 so that, when casing 16 is disposed within housing 11 with the bottom of the casing adjacent the bottom opening of housing 11, as shown on FIGS. 1 `and 3, a compartment 18 is defined within housing 11 above heating units 15. A conduit or duct 19 (FIGS. 1 and 3) opens into compartment 18 through top wall 12 of housing 11 so that a gaseous medium, such as air, can be introduced into compartment 18 through conduit 19 for exit from housing 11 through the clearances 17 extending along the opposite sides of each heating unit 15.

The casing 16 of each heating unit 15 contains means for emitting infra-red radiation downwardly from the bottom of the casing and for heating the latter. In the illustrated embodiment of the invention, such means for mitting radiation and heating the casing is shown to include electrical Aresistance heating elements or wires 20 positioned in grooves of a ceramic support plate 21 which overlies a fused quartz plate 22. Quartz plate 22 extends over the entire bottom of casing 16 and is suspended by means of inwardly directed flanges 23 along the periphery of casing 16 at the bottom thereof. Disposed above ceramic support plate 21 is suitable insulation, which may be in the form of successive insulating layers 2-4 and 25 of ceramic or glass wool and of asbestos wool or fibers, respectively. -Electric power for energizing resistance heating elements 20` may be supplied thereto through suitably insulated conductors entering compartments 18 through duct 19 or through one of end walls 14 and being connected to terminals (not shown) provided on each casing 16.

When resistance heating elements 20 are energized, infra-red radiation is directed downwardly from the surface of fused quartz plate 22 at the bottom of each casing 16 against the underlying moving web W. Simultaneously, casing 16 of each heating unit is heated so that the air entering housing 11 through conduit 19 and issuing therefrom through clearances 17 absorbs heating from each casing 16 thereby to prevent overheating of the casings 16 and to ensure that the air flows passing through clearances 17 for impingement on the moving web a-re suitably heated, for example, to a temperature of approximately 250i to 300 F. for enhancing the drying effect.

Since electrical resistance heating wires or elements, as embodied in each heating unit 15, are relatively prone to failure, each heating unit 15 is individually mounted in housing 11 in a manner to facilitate its quick removal and replacement. In accordance with this invention, such mounting of each heating unit 15 within housing 11 is eected by means of ears 26 projecting laterally from the opposite sides of casing 16 adjacent to top thereof and being releasably engageable by mounting brackets 27 which are fixed to the adjacent side walls 13 of housing 11.

As shown particularly on FIG. 4, each mountlng bracket 27 is in the form of a strip of spring steel or other resiliently flexible material having a lower or base portion 28 which is spot-welded, as at 29, or otherwise suitably secured to the inner surface of side wall 13. Bracket 27 further has an upper angled portion 30` inclined inwardly and upwardly from base portion 28 so as to normally diverge from side wall 13 and thus be biased towards the adjacent side of casing 16. The inclined upper portion 30` has a slot 31 adjacent its upper end which is dimensioned to receive the associated ear 26 projecting from casing 16, and an inwardly directed flange 32 extends from the upper end of portion 30- and has a width greater than the distance that the ear 26 projects laterally beyond the side of casing 16.

As shown particularly on FIG. 2, each heating unit 15 may be mounted within housing 11 by two ears 26 and associated mounting brackets 27 disposed adjacent the opposite ends of its casing 16 at one side of the latter and by a single ear 26 and associated mounting bracket 27 located mid-way between the ends of casing 16 at the opposite side of the latter. However, it is apparent that two ears and associated mounting brackets may be provided at each of the opposite sides of the casing adjacent the opposite ends thereof.

When a heating unit 1S is fto be installed in housing 11, such heating unit is merely moved upwardly into the housing through the open bottom thereof, as shown on FIG. 6, with casing 16 being located longitudinally relative to housing 11 so that its ears 26 will register with the respective mounting brackets 27. As casing 16 is displaced upwardly relative to housing 11, ears 26 will bear against the inwardly inclined resilient portions 30 of the mounting brackets and cause outward deflection of such resilient portions 30 until ears 26 are aligned with and enter into slots 31 of the respective mounting brackets. In the course of such upward movement of casing 16 relative to housing 11, flanges 32 at the upper ends of resilient portions 30 will extend over the top surface of casing 16 even when such resilient portions 30 are deflected outwardly by ears 26, thereby to prevent excessive upward movement of casing 16 beyond the position where its ears 26 will enter slots 31. Upon the entry of ears 26 into slots 31 casing 16 is securely suspended by mounting brackets 27 with the sides of casing 16 being spaced from side walls 13 of the housing to provide the requisite clearances 17 therebetween for the flows of air therethrough during operation of the drying apparatus.

In the event of the failure of the resistance heating wires or elements 20 of a heating unit 15, or whenever the removal of such heating unit is required for any other reason, such removal can be quickly and easily effected, as shown on FIG. 5, merely by inserting a screw driver 33 or other suitable tool upwardly into clearance 17 and rocking such tool against portion 30 of each bracket 27 so as to outwardly deflect such resilient portion 30 to an extent sufficient to release the associated ear 26 from its slot 31. Upon release of each ear 26 from the slot 31 of the respective bracket 27, the heating unit 15 is free to drop downwardly through the open bottom of housing 11. Thus, each of the heating units 1S within housing 11 can be quickly and conveniently replaced in the event of the failure thereof or whenever removal of the heating unit is required for maintenance of the drying apparatus. Such removal of each heating unit 15 can be effected independently of the other heating units within housing 11 and requires only a relatively short period of inoperativeness of the production line with which the heating apparatus is associated.

Although the present invention has been illustrated as applied to a heating apparatus 10 having a single elongated housing 11 extending laterally across the moving web W, it is apparent that a plurality of such housings 11 can be arranged one after the other in the direction of movement of the web so as to achieve a correspondingly increased drying effect.

In the foregoing, a specific embodiment of the invention has been described in detail with reference to the accompanying drawing, but it is to be understood that the invention is not limited to that precise embodiment, and that various changes and modifications may be effected therein by one skilled in the art Without departing from the scope or spirit of the invention as defined in the appended claims.

What is claimed is:

1. A dryer for drying articles by the combination of infra-red radiations and air, the combination of an elongated housing which is open at the bottom, at least one heating unit including a metal casing dimensioned to ht in said housing with substantial clearance between the sides of said housing and casing and containing means to emit infra-red radiations downwardly from the bottom of said causing and to heat the latter, said housing having an inlet for air above said casing so tha-t such air issues from the bottom of said housing through said clearance and is heated by absorbing heat from said casing, and means to removably mount each said heating unit in said housing including ears projecting laterally outward from said sides of the casing and associated mounting brackets secured to said sides of the housing and including resiliently exible portions biased towards said casing and having slots to receive said ears, said flexible portions being displaceable away from said casing to release said ears and thereby permit removal of each said heating unit from the housing.

2. A dryer according to claim 1, in which said resiliently flexible portion of each mounting bracket is in the form of a strip inclined away from the adjacent side of said housing in the upward direction and having said slot in the upper part of the strip so that, during upward insertion of saidheating unit into said housing, said ears can outwardly deect the resilient strips of said brackets until said ears are received in said slots.

3. A dryer according to claim 2, in which said strip of each mounting bracket has an inwardly directed flange at its upper end to engage over the top of said casing and limit the upward movement of the casing to a position where said ears register with said slots.

4. A dryer according to claim 1, in which said housing has a length which is at least two times as large as the length of said casing of each said heating unit, and there are a plurality of said heating units arranged end-to-end in said housing and individually mounted in the latter by respective mounting brackets.

References Cited UNITED STATES PATENTS 1,961,179 6/1934 Tinkham 34-243 2,389,586 11/1945 Andrews 34-68 3,141,089' 7/1964 Hultgreen 219--352 l FREDERICK L. MATTESON, IR., Primary Examiner HARRY B. RAMEY, Assistant Examiner 

